Valve attenuator for internal combustion piston engines

ABSTRACT

A valve control assembly for internal combustion piston engines whose rocker arm is linked to an attenuator member which member is designed in such a manner that the attennuating effect exerted thereby is decreased as the engine speed is increased so that an optimum opening movement of the valve is obtained for any speed up to maximum speed.

United States Patent 1 01,846 8/1911 Harley.

Willy Bartels Julicher Str. 56, Dusseldorf, Germany 705,204

Feb. 13, 1968 Feb. 16, 1971 Inventor App]. No. Filed Patented VALVE ATTENIJATOR FOR INTERNAL COMBUSTION PISTON ENGINES 8 Claims, 11 Drawing Figs.

References Cited UNITED STATES PATENTS 1,204,520 11/1916 Tuttle l37/514.7 1,379,180 5/1921 Good 251/54X 1,931,476 10/1933 Hallett 123/90 2,014,659 9/1935 Mocrhouse 123/90 2,117,421 5/1938 Holden 251/54 2,117,434 5/1938 Krebs 123/90 2,348,383 5/1944 Hedgecock... 137/514 3,298,337 l/1967 Thomps0n.... 123/90X 2,332,280 10/1943 Udale 123/90(K3) 3,403,663 10/1968 Wagner 123/90(l(3) Primary Examiner-Al Lawrence Smith Altomey- Burgess, Dinklage & Sprung ABSTRACT: A valve control assembly for internal com- Patented Feb. 16,1971 4 3,563,217

5 Sheets-Sheet 2 Patente d Feb. 16, 1971 3,563,217

5 Sheets-Sheet I lnvenfor:

Patented Feb, 16, 1971 s Sheets-Sheet s' lnvenfor:

VALVE ATTENUATOR FOR INTERNAL COMBUSTION PISTON ENGINES This invention generally refers to internal combustion piston engines, and in particular is concerned with valve assemblies for such engines. V

The degree to which the cylinder of internal combustion piston engines is filled by the explosive mixture and correspondingly by the power of suchan engine, largely depends on the time for which its intake and its exhaust valves are opened or closed, respectively. At high speeds, the power of such a piston engine can be increased by extending the opening time of the intake valve, namely by advancing the point at which the valve is opened and by delaying the point, at which it is closed. However, at lower speeds, such an extended opening time would reduce power and likewise cause irregular rotation of the engine and noxious gases.

The opening time of an intake valve of piston engines normally is determined by the form of a control element rotating in correspondence with the crankshaft of the engine, such a control element generally being constituted by a cam driven by a camshaft and actuating'a rocker arm which in turn is capable of moving the stem of a valve against the action of a suitable coiled spring. The movement performed by the valve therefore corresponds more or lessexactly to the configuration of the cam which positively drives that valve. Such a cam, therefore, normally has a configuration guaranteeing an optimum merely at a certain medium speed; at low speeds however this cam causes opening times that are too long, albeit that the engine may still run in a sufficiently smooth manner, whereas at high speeds, these opening times are too short. With regard to the exhaust valve, it is likewise suitable to vary the opening and closingtimes'responsive to the engine speed.

Former suggestions to adjust the control times of the valves in correspondence to the engine speed such that the valve opening is kept at an optimum regardless of the speed may be carried into effect only at comparatively high expenses and.

therefore did not grow beyond an experimental status.

It is therefore an object of this invention to provide a valve assembly for internal combustion piston engines by means of which the opening and closing movement of the valve may be controlled by simple means in such a manner that the closing and the opening movement is an optimum, i.e. that the valve will close and open with. regard to the respective speed at the most appropriate point at any speed of the engine up to the nominal maximum speed. 7

Accordingly, this invention provides a valve control assembly in which the valve is associated with a suitable attenuator means. This attenuator means is so designed that the dos ing point of the valve will remain unaffected at comparatively low speeds, but will be delayed by a certain'time growing as the speed of the engine grows. In addition, according to this invention, the valve actuating assembly may be so designed that the period during which the valve is kept open may be shifted as whole with regard to the respective position of the piston so that the valve at higher-speeds will open at an earlier point, whereas the opening in time will depend merely on the. effect of the attenuator. The shifting of the opening and closing point, respectively, may be accomplished by changing the relative angular position of the cam shaft with regard to the,

rocker arm by means of an arrangement driven by the engine and responsive to centrifugal forces. The amplitude of the opening and closing movement of the valve may be controlled by a suitable reset spring having a nonlinear, e.g. a square-law, characteristic. j

The present invention will be more fully understood from the following description of embodiments thereof in connection with the accompanying drawings in which:

FIG. I is an elevational view of a valve control assembly according to this invention in its association with the housing of an internal combustion piston engine indicated by a fragmentary sectional view;

FIG. 2--7 show charts illustrating under various conditions the valve movement versus rotation of the crank shaft as measured by angular degrees or by time units; and

V biased in its closed position by means of a spring 8 acting in upward direction against a disc 10 secured to the upper end of a stem 6 of valve 7.

Valve 7 is actuated (i.e. opened and closed) by means of a cam 2 rotating together with a cam shaft 1, which cam 2 engages the rear end of a rocker arm 4 pivotally mounted on a a shaft 3. The front end of rocker arm 4 engages the upper end of stem 6 in a biased manner by means of an adjustable boss 5.

An attenuator member 12 is interconnected between the rear arm portion of rocker arm 4 and a housing 9 of the engine.

If there is no attenuator member 12 provided, as is normally the case, the movement of c valve 7 will correspond precisely to the contours of cam 2. This movement is represented by the continuous line A of FIG 2. In the diagram of FIG. 2, the displacement s of valve 7 is plotted versus the rotation of the crankshaft, this rotation being indicated by the angles KW of said crankshaft. FIG. 2'is based on a four-stroke engine whose intake stroke takes place within a crankshaft angle of from 0 to 180, so that valve 7 will begin to open at an angle of 0 and will close at an angle of 180.

With an engine having a maximum speed of 6,000 r.p.m. at speeds Map to 2,000 r.p.m. the optimum opening and closing periods of the valve would correspond to the characteristic A of FIG. 2. However, at a speed of 4,000 r.p.m. such an optimum opening and closing time would correspond to curve B, and at a speed of 6,000 r.p.m. this time would correspond to curve C. Consequently, at a speed of 4,000 r.p.m. and 6,000

r.p.m. the point at which opening commences must be advanced by 15 or 30 KW, respectively, whereas the closing point must be deferred by 40 or KW, respectively, so that the complete opening time will be increased by 55 or Il0 KW, respectively, i.e. by about 30 percent or 60 percent, respectively. By this'invention such an adaptation of the characteristics of the valve movement will be made possible by simple means not requiring additional attention or control.

FIGS. 3 and 4 represent theeffect of the hydraulic attenuator member 12 linked to rocker arm 4, on the assumption that the engagement between valve 7 and the rotating control element, for example cam 2 of FIG. 1 is interrupted during the opening time as soon as a certain motor speed is exceeded, for example2,000 r.p.m. with an engine of a maximum speed of 6,000 r.p.m.

Thus, curve A of FIG. 3 shows-in the same manner of as curve A of FIG. 2-the movement of the valve with reference to a situation in which the valve is in engagement with the cam 2 of camshaft 1. Hence, the configuration of curve A corresponds to the shape of cam 2.

Curve D of FIG. 3 represents a situation in which the positive connection between cam and valve is interrupted at a higher speed of the engine as soon as the valve has received at point b of its opening path a velocitycorresponding to the angle athis being the velocity at which the valve will then continue its movement in a flying manner, so that its velocity is not controlled by the cam anymore, but merely by its mass and the initial velocity imparted to it at point b as well as by forces acting opposite to the movement of the valve, in particular the force exerted by the spring 8 of FIG. I. The valve velocity of the valve assumed at point b depends on the speed of the cam and therefore on the speed of the crankshaft. Since the abscissa of FIG. 3 does not correspond to time, but to the angle of the crankshaft, the angle 0: indicated at point b of FIG. 3 corresponds to a valve velocity which is linearly different for different speeds of the engine. FIG. 4 represents the same curves of FIG. 3 with an abscissa marked in time units of milliseconds.

At a speed of 4,000 r.p.m. (curve D) the velocity of the valve at point b is twice that of the valve velocity at a speed of 2,000 r.p.m. Accordingly, its motional energy is increased four times. Since virtually merely reset spring 8 is effective, the valve in this case is displaced by a distance ud-provided a linear characteristic of spring 8-which distance ((-11 is substantially larger than the distance a-traversed in connection with curve A.

At a speed of 6,000 r.p.m., the valve, according to the still greater velocity imparted thereto at point b travels a still greater distance, i.e. according to the curve E on to the apex e. Upon having reached the apex d or e, respectively, the valve is closed under the influence of the reset spring 8. As indicated by the respective portions of curves D and E, respectively, this return movement will occur at such a great velocity (as illustrated by angle B) that the valve head would strike its valve seat so violently that both parts would be destroyed. Such heavy impact of the valve could be prevented by attenuating the valve when it has travelled beyond the apex of the respective curve by means of a conventional attenuator in such a manner, that closing of the valve will take place according to an e-function. Due to this, however, the closing point of the valve would be too much delayed. In FIG. 3, the effect of a conventional hydraulic attentuator is illustrated in dashed line. In order to obtain by means of such an attenuator a sufficiently low closing velocity of the valve, the closing point would be shifted to such an extent, that at higher speeds the engine could not run properly. At a speed of 6,000 r.p.m., the closing point would even be located more than 360 behind the point at which the valve opens, so that the valve would remain open during the entire compression stroke, with no compression taking place at all.

FIG. shows the movement of the same valve and at the same different speeds, i.e. 2,000, 4,000 and 6,000 r.p.m., as considered in connection with FIGS. 2-4, but with an attenuator member according to this invention being employed. Again, a curve A represents the movement of the valve at an engine speed of 2,000 r.p.m., at which speed the valve is engaged with the cam of the camshaft during its entire move ment. By replacing the conventional reset spring of linear characteristic with a reset spring having a square characteristic, the amplitude of the apex d of the curve d,, which curve otherwise corresponds to curve D of FIG. 3, does not even amount to twice the height of the amplitude of apex c of curve A. Similarly, the amplitude of curve B at apex point e corresponds to merely about three times the amplitude of curve A at apex point 0. By means of an attenuator as the attenuator member 12 of FIG. 1, the descending portion of curve D is altered in such a manner, that the valve is closed upon a comparatively short closing movement and that the closing point is reached at an angle of about 235, as this illustrated by the dashed curve D By turning the camshaft such that the opening point of the valve is advanced by l5, i.e. on to point aD the entire curve D is shifted to the left by these l5, so that curve D is obtained whose closing point will be located at an angle of 220. This curve D will have the same optimum opening an and closing points as curve B of FIG. 2, corresponding however to a larger valve stroke.

In order to achieve optimum opening and closing points for the valve in such an arrangement not only a speed of 4,000 r.p.m. but for any speed of the engine up to the maximum speed of 6,000 r.p.m., the effect exerted by the attenuator must by reduced in accordance with the engine speed. Curve E of FIG. 5 corresponds to the behavior of the valve at a speed of 6,000 r.p.m. when influenced by an attenuator member of this application, whereas curve E is illustrative of the path of the valve when the cam shaft is rotated about an angle of 30; again this curve 5;, corresponds to the optimum curve C of FIG. 2, having however a larger valve stroke.

The attenuators shown in FIG. 8 and 9 are designed for a situation in which the valve is positively engaged by the cam only during a portion of its opening movement.

The attenuator of FIG. 8 includes a potlike member filled with a liquid capable of exerting an attenuating effect, such as oil, and having a wall whose outer surface is of cylindrical configuration. This potlike member is closed by a bottom 122 integral with wall 120 as well as by a cover member 121. Within a said potlike member, there is a piston constituted by a rigid disc 123 whose piston rod 13 may be joined with rocker arm 4 as illustrated in FIG. 1. Disc 123 divides the interior of the potlike member into two chambers 131, 132. It is provided with two openings 126, through which the liquid contained in the potlike member may flow from one of the two chambers 131, 132 into the other one. Disc 126 is mounted onto a portion 124 of enlarged diameter in an axially movable manner between a lower plate 125 having a diameter smaller than the distance of openings 126 from the axis of stem 13, respectively, and between an upper plate 129 having a diameter greater than the distance of openings 126 from the axis of stem 13, so

that the upper plate 129 may cover openings 126. At its inner surface, wall 120 is slightly tapered, so that the inner diameter of the potlike member in the proximity of its bottom 122 is only little larger than the outer diameter of disc 123, and so that the inner diameter at the upper end of wall 122 is larger than at its lower bottom end. The piston rod 13 is guided through a packing 128 held by the cover member 121. Outside cover member 121, piston rod 13 is protected against contamination by an elastic sleeve 130. Inside the potlike member 120, there is mounted an air filled hose 127. When the valve 7 is in its closed p9sition, as shown in FIG. 1, disc 123 is located near bottom 122. When cam 2 moves the engaging end of rocker arm 4 in upward direction, thereby opening valve 7, disc 124 is likewise moved in upward direction through piston rod 13. During this upward movement, disc 123 is supported on plate 125, so that the liquid may flow freely through the openings 126 from chamber 131 into chamber 132. As a result, the opening movement of the valve is not affected. Upon commencement of the closing movement of the valve, piston rod 13 is moved in downward direction. Disc 123 will then contact plate 129 which, in turn, will close openings 126, so that merely an annular gap 133 between the outer edge of disc 123 and the inner surface of wall 120 will be left for the passage of liquid from chamber 132 to chamber 131. Due to this flow resistance, the velocity of the valve is decreased during the entire closing movement.

At engine speeds of up to 2,000 r.p.m., disc 123 will be kept within the range designated A-B, up to a speed of 4,000 r.p.m. it will, in accordance with the longer path of the valve, travel within the range designated AD, and at a speed of 6,000 r.p.m. it will travel within the range designated A-E. For the range AB, the gap 133 is so designed, that the curve of the valve movement at a speed of well up to 2,000 r.p.m. practically corresponds to the curve of movement as predetermined by the cam. Within the area B-E gap 133 is enlarged in such a manner, that a valve movement according to the curves D and E of FIG. 5 is obtained.

The attenuator represented in FIG. 9 is different from that of FIG. 8 chiefly insofar as the enlargement of the gap between the piston and the wall of the potlike member is accomplished primarily due to an tapered configuration of the piston rather than by a conical shape of the inner surface of the wall 120 as provided in FIG. 8. The attenuator of FIG. 9 comprises a cylindrical housing which, by means of a partition 223 extending in a direction parallel to a bottom 222, is divided into an upper chamber 231 and a lower chamber 232. At its upper side, the cylindrical housing is closed by a diaphragm 221. Partition 223 is provided with an opening 226 receiving a valve member 224, which normally is kept in its opened position by means of a spring 225 but is capable of closing opening 226 when forced into this opening against the action of the spring 225.

At its outer side, diaphragm 221 is connected to a rod 13, that may be attached to the rocker arm 4 of FIG. 1. A piston 230 tapered toward bottom 222 is threadedly engaged with rod 13 and extends through a bore 233 provided in partition 223. The diameter of bore 233 is somewhat larger than that of the upper end of piston 230. At its lower end, piston 230 terminates into a head member 228 axially guided in a socket 229 provided at bottom 222. An air filled hose 227 is located in chamber 232 for compensation of volume.

Piston 230 is moved in correspondence with valve 7 in such a manner, that at a speed of 2,000 r.p.m. its lower end will move within the range A-C, within range A-D at a speed of 4,000 r.p.m., and with range A- -E at a speed of 6,000 rpm. Along a material portion of the piston movement the width of gap 233 will therefore grow as the speed of the engine is increased. a

FIG. represents a further embodiment of an attenuator according to this invention designed for a situation in which the movement of valve 7 is controlled by the shape of cam 2 during its entire opening movement, so that the engagement between the valve and the cam is terminated only at the moment of maximum opening of the valve, as demonstrated by the curves of FIG. 6 and 7. Reduction of the attenuation corresponding to the speed of the engine is here caused by a throttle moved in accordance with the speed by a centrifugal force.

Thus, the attenuator of FIG. 10 differs fromthe attenuator of FIG. 9 chiefly insofar as first the chamber 422 from which the liquid escapes into chamber 421 during the opening of the valve is here in communication with a third chamber 423, second the arrangement for pressure compensation, which in FIG. 9 is constituted by the air filled hose 227, is provided within the chamber 423, and third that a slide member .424 controlled by a governor 434 is located within a passage 422 through which chambers 422 and 423 communicate with each other.

As demonstrated by FIG. 10, this governor may be a conventional centrifugal governor, driven by a preferably toothed belt 435 in correspondence to the speed of the engine in such a manner, that opening 438 as defined by slide member 424 is.

increased when the speed of the engine is raised. Slide member 424 is provided with an opening 430 that may be closed by a check valve 438. Chamber 423 is formed as a container for hydropneumatic compensation. It is provided with a diaphragm 432a and a opening 423b, that may be tightly sealed. A gas may be filled through opening 42311 and pressurized to such an extent, that the desired counteraction on piston 432 is attained.

Piston 432 of FIG. 10 includes an upper section 4320, a center section 432b, and a lower section 432a The cross section of upper section 432a is such, that the liquid will encounter a very great flow resistance in gap 433 when upper section 43211 is shifted into gap 433. The central section 432b is of substantially smaller cross section, whereas the cross section of lower section 432a is substantially as large as that of upper section 432a.

In operation of this attenuator of FIG. 10, when valve 7 is opened, liquid may flow from chamber 423 into chamber 421 in an unobstructed manner, since the check valve 438 is in its opened position. When valve 7 begins to become closed, check valve 438 will likewise assume its closed position, so that merely the passages 433 and 438 will be available for the passage of liquid tending to flow from chamber 421 into chamber 423. If piston 432 would be of cylindrical shape, the movement of rod 13 and consequently valve 7 would be attenuated during the entire closing movement in a constant manner. The closing movement would then take place in compliance with an e-function. Such an e-function is evident from curve F of FIG. 6. In order to obtain the movement of valve 7 as represented by curve F which in comparison with curve F has the advantage of a lower flow resistance at valve 7 and, as a result thereof, the advantage of a better filling of the cylinder of the engine, piston 432 is stepped as shown in FIG. 10. Due to the large cross section of portion 4320, at first a very intensive attenuation of the valve movement will take place, so that curve F will be lowered only slightly; as soon as section 432b will reach opening 433, the attenuation effect is decreased considerably, so that curve F will rapidly descend; as soon as the upper section 432a will become effective, this attenuation is again increased, so that curve F is flattened to such an extent, that it intersects the abscissa at the desired crankshaft angle at a very low velocity.

Normally, it would be uneconomical to equip each attenuator with a centrifugal governor. In view thereof, the slide members 424 of all attenuators of one engine could be actuated through suitable connection means by one common centrifugal governor.

FIG. 11 shows an attenuator of similar behavior as the attenuator of FIG. 10, having however two different pistons or plungers 32 and 37, piston 32 corresponding to piston 432 of FIG. 10 and piston 37 corresponding to slide member 424 of FIG. 10.

The attenuator of FIG. 11 comprises a cylindrical housing 14 closed at its lower end by a bottom 15 and at its upper end by a diaphragm 16 held in position on top of housing 14 by means of a ring 18v and by suitable: bolts in a sealed, but detachable manner. The interior of housing 14 is divided into three chambers 21, 22, 23 by means of two partitions l9 and 20, communicating with each other through central bores 33, 38, furthermore through openings 26, 30 which may be closed by check valves 24 and 28 against the influence of springs 27, 31 arranged between partition 19 and 20, respectively, and a plate 25 and 29, respectively, connected with valve 24 and 28, respectively. The rod 13 sewing for connection with the rocker arm 4 extends through the center of diaphragm 16 with a threaded portion 13a screwed into piston 32, which extends through bore 33, so that an annular gap is defined.

The second piston section 37 is tapered in upward direction and extends through an opening 38 of the second partition 20,

so that a second annular gap is defined between the rim of bore 38 of partition 20 and the outer surface of piston 38. At its lower end, piston 37 terminates into a cylindrical protrusion having axial grooves 40 engaging with corresponding guide rails of a sleeve 41 integral with bottom 15. The space below protrusion 39 communicates with chamber 23 through a bore 43. A coil spring 42 is positioned between the upper surface of sleeve 41 and the lower surface of piston 37. An upper cylindrical extension 35 of piston or plunger 37 fits into a bore 34 of plunger 32. This cylindrical extension has axial slots 36 and, at its upper end, carries a. flutter valve 360 which largely closes the entrances of the several grooves due to a surplus liquid pressure prevailing in bore 34, i.e. which opens whenthe liquid pressure prevailing in chamber 22 exceeds that of bore 34. An air filled hose arranged in chamber 23 provides for a balance in volume.

Pistons or plungers 32 and 37 may readily be exchanged upon removal of diaphragm 16, so that the behavior of the attenuator may readily be adapted to various types of engines and kinds of operation.

In the attenuator of FIG. 11, chambers 21 and 23, piston 32, and opening 33 correspond to the chambers 231 and 232, piston 230 and opening 233, respectively, of FIG. 9. While valve 7 (FIG. 1) during its opening movement travels on the apex c of curve A of FIGS. 6 and 7, thereby shifting rod 13 and diaphragm 16 in upward direction, liquid will flow from chamber 23 through opening 30, chamber 22 and opening 26 into chamber 21 in a substantially unobstructed manner. When the opening movement of the valve is at its maximum, opening piston 32 will have assumed its uppermost position in which it closes gap 33 almost entirely. At the beginning of the closing movement of valve 7 as caused by spring 8, i.e. upon apex c has been passed, openings 26 and 30 will be closed, since the liquid pressure prevailing in chamber 21 will exceed that of chamber 22, whereas the pressure prevailing in chamber 22 will exceed that of chamber 23. Liquid may therefore flow chamber 21 to chamber 22 only through the very narrow gap 33, so that the downward movement of rod 13 is retarded and, as a result thereof, the closing movement of valve 7 is likewise retarded, which then will not follow the configuration of the cam anymore. Due to the stepped contours of piston 32 which correspond substantially to the stepped contours of piston 432 of FIG. 10, gap 33 at first is scarcely altered during the downward movement of rod 13, will then be enlarged appreciably and subsequently again will be substantially narrowed so that the particularly suitable shape of curve F l of FIG. 6 is obtained for the valve movement.

By means of piston 37, the flow of liquid through gap 38 may be reduced the more the speed of the engine is decreased. At a low speed, piston 37 will be moved in upward direction under the influence of spring 42. Liquid such as oil having entered bore 34 via grooves 36 during the opening movement of valve 7, at a low speed may return into chamber 22 through grooves 36 during the closing movement of valve 7. The more the speed will grow, the less oil may escape from bore 34 via grooves 36 which during the closing movement are narrowed by the flutter valve 36a. Thus, piston 37 will be moved in downward direction in response to the speed of the engine, so that the gap 38 will become wider the more the speed is increased. Consequently, the attenuation effect is decreased with the increase in speed. By means of the common effect of the pistons 32 and 37, curves A, F, and G as represented in FIG. 6 may therefore be obtained for the engine speed of 2,000, 4,000 or 6,000 rpm, respectively, and upon having shifted curve F and G,, the optimum curves G G of FIG. 7 may be obtained.

lclaim:

1. In an internal combustion piston engine wherein gases are admitted to and/or removed from a cylinder through a valve port which is cyclically opened and closed synchronously with the movement of a piston in said cylinder by means ofa valve, said valve being so opened by a valve actuator and so closed by a valve spring, and wherein above a certain minimum engine speed said valve after being initially set in motion during its opening movement, opens at a greater rate than the rate of movement of said valve actuator and loses contact therewith, said contact being reestablished during the closing movement of said valve; an attenuator means adapted to regulate said opening and closing movementsof said valve and to effect a substantially shock-free closing of said valve, comprising:

1. a fixedly mounted dampening chamber filled with an incompressible dampening fluid;

2. a dampening piston mating with said dampening chamber, but providing a passageway therebetween, the relationship between the two being such that during the closing movement of said dampening piston into said dampening chamber the free cross-sectional area of said passageway decreases thus increasingly impeding the flow of said dampening fluid from the underside of said dampening piston through said passageway to the upper side thereof;

. an orifice conduit with an associated check valve means connecting the fluid reservoir beneath said dampening piston with the fluid reservoir thereabove, said check valve means closing said orifice conduit during said closing movement of said dampening piston and opening the same during the reverse movement thereof; and

4. a connecting means fixedly connecting said dampening piston to said valve so that the closing movements of each occur together, the decreasing of said free cross-sectional area towards the end of said closing movement being sufficient to secure substantially shock-free closing of said valve.

2. The attenuator means of claim I wherein said dampening chamber is essentially a single chamber with said dampening piston therein dividing it into two portions, the internal walls of said dampening chamber being tapered with respect to the closing movement of said dampening piston to effect the decrease in said free cross-sectional area, wherein said orifice conduit is located in said dampening piston, and wherein said dampening piston is a disc having a limited movement with respect to said connecting means sufficient to seat said orifice conduit against said check valve means during said closing movement, said check valve means being a disc mating with said dampening piston extending over said orifice conduit and rigidly mounted on said connecting means.

3. he attenuator means of claim 1 wherein said dampening chamber comprises two compartments divided by a wall containing said passageway through which said dampening piston extends, which wall also contains said orifice conduit, said check valve comprising a spring-loaded plunger mating within said orifice conduit, said dampening piston being tapered with respect to the sides of said passageway to effect the decrease of said free cross-sectional area during said closing movement.

4. The attenuator means of claim 1 wherein said dampening chamber contains in fluid contact with said dampening fluid a pressure-compressible member adapted to maintain the fluid volume with said dampening chamber substantially constant.

5. The attenuator means of claim 1 including in addition advancing means for shifting the moment of opening of said valve by said valve actuator as measured by angular degrees of engine revolution as the speed of said engine increases, the valve stroke becoming relatively larger as the movement of valve opening is advanced by reason of the action of said attenuator means.

6. The attenuator means of claim 1 wherein the relationship between said dampening chamber and said dampening piston is such that said free cross-sectional area of said passageway decreases during the terminal portion of the open movement of said dampening piston so that the attenuation effected is greater during the terminal portions of said opening and closing movements than during the middle portions thereof.

7. In a valve control assembly of an internal combustion engine having: valve means including a valve reciprocally mounted within the housing of said engine by means of an actuating stem and adapted to open and close intake and exhaust ports communicating with a cylinder of said engine; reciprocating means adapted to engage and move said valve means from a closed to an open position thereof synchronously with the degree of rotation of said engine; a spring means acting against said reciprocating means and adapted to bias said valve in its closed position; the improvement comprising: attenuator means associated with said reciprocating means and adapted to modify the motion of said valve means as actuated by said reciprocating means, said attenuator means comprising a container having a first chamber and a second chamber communicating with said first chamber through an orifice, said first and second chambers being filled with an attenuating liquid, a piston means extending through said orifice and connecting to said reciprocating means to move correspondingly to the movement of said valve means, the relationship of said piston means and said first and chamber being such that the flow resistance offered by said orifice is higher at the termination of the closing movement of said valve means than during the intermediate movement thereof, and a passageway with-an associated check valve connecting said first chamber with said second chamber, said check valve being adapted to close said passageway during said closing movement and open the same during the opening movement whereby said attenuator fluid can flow through said passageway, such that the attenuation effected by said attenuator occurs primarily during said closing movement.

8. The valve control assembly of claim 7 wherein the walls of said piston and/or said second chamber are tapered such that as said piston descends into said second chamber a greater amount of said attenuating fluid must be displaced therefrom for each increment of descent of said piston.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,563,217 Dated raury 16, 1971 Inventofls) rtels It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 18 cancel "(1"; line 51 cancel "of" secor occurrence; line 59 "ozthiS" should read d this Column line 41 "d should read D line 51 after "this" inse1 is line 53, "aD should read a Column 4 line 1 after "within" cancel "a"; line 27 "p9siti0n" should read position line 30 "124" should read 123 line 57 "an" should read a Column 5 line 29 "422" should read 422a line 40 "a" should read an line 48 "432b" first occurrence should read 432a-- Signed and sealed this 14th day of September 1971 (SEAL) Attest:

E ZE Z Z E- SEE E JR. 120mm GOTTSCHALK g Acting Commissioner of Pate] 

1. In an internal combustion piston engine wherein gases are admitted to and/or removed from a cylinder through a valve port which is cyclically opened and closed synchronously with the movement of a piston in said cylinder by means of a valve, said valve being so opened by a valve actuator and so closed by a valve spring, and wherein above a certain minimum engine speed said valve after being initially set in motion during its opening movement, opens at a greater rate than the rate of movement of said valve actuator and loses contact therewith, said contact being reestablished during the closing movement of said valve; an attenuator means adapted to regulate said opening and closing movements of said valve and to effect a substantially shock-free closing of said valve, comprising:
 1. a fixedly mounted dampening chamber filled with an incompressible dampening fluid;
 2. a dampening piston mating with said dampening chamber, but providing a passageway therebetween, the relationship between the two being such that during the closing movement of said dampening piston into said dampening chamber the free crosssectional area of said passageway decreases thus increasingly impeding the flow of said dampening fluid from the underside of said dampening piston through said passageway to the upper side thereof;
 3. an orifice conduit with an associated check valve means connecting the fluid reservoir beneath said dampening piston with the fluid reservoir thereabove, said check valve means closing said orifice conduit during said closing movement of said dampening piston and opening the same during the reverse movement thereof; and
 4. a connecting means fixedly connecting said dampening piston to said valve so that the closing movements of each occur together, the decreasing of said free cross-sectional area towards the end of said closing movement being sufficient to secure substantially shock-free closing of said valve.
 2. a dampening piston mating with said dampening chamber, but providing a passageway therebetween, the relationship between the two being such that during the closing movement of said dampening piston into said dampening chamber the free cross-sectional area of said passageway decreases thus increasingly impeding the flow of said dampening fluid from the underside of said dampening piston through said passageway to the upper side thereof;
 2. The attenuator means of claim 1 wherein said dampening chamber is essentially a single chamber with said dampening piston therein dividing it into two portions, the internal walls of said dampening chamber being tapered with respect to the closing movement of said dampening piston to effect the decrease in said free cross-sectional area, wherein said orifice conduit is located in said dampening piston, and wherein said dampening piston is a disc having a limited movement with respect to said connecting means sufficient to seat said orifice conduit against said check valve means during said closing movement, said check valve means being a disc mating with said dampening piston extending over said orifice conduit and rigidly mounted on said connecting means.
 3. The attenuator means of claim 1 wherein said dampening chamber comprises two compartments divided by a wall containing said passageway through which said dampening piston extends, which wall also contains said orifice conduit, said check valve comprising a spring-loaded plunger mating within said orifice conduit, said dampening piston being tapered with respect to the sides of said passageway to effect the decrease of said free cross-sectional area during said Closing movement.
 3. an orifice conduit with an associated check valve means connecting the fluid reservoir beneath said dampening piston with the fluid reservoir thereabove, said check valve means closing said orifice conduit during said closing movement of said dampening piston and opening the same during the reverse movement thereof; and
 4. The attenuator means of claim 1 wherein said dampening chamber contains in fluid contact with said dampening fluid a pressure-compressible member adapted to maintain the fluid volume with said dampening chamber substantially constant.
 4. a connecting means fixedly connecting said dampening piston to said valve so that the closing movements of each occur together, the decreasing of said free cross-sectional area towards the end of said closing movement being sufficient to secure substantially shock-free closing of said valve.
 5. The attenuator means of claim 1 including in addition advancing means for shifting the moment of opening of said valve by said valve actuator as measured by angular degrees of engine revolution as the speed of said engine increases, the valve stroke becoming relatively larger as the movement of valve opening is advanced by reason of the action of said attenuator means.
 6. The attenuator means of claim 1 wherein the relationship between said dampening chamber and said dampening piston is such that said free cross-sectional area of said passageway decreases during the terminal portion of the open movement of said dampening piston so that the attenuation effected is greater during the terminal portions of said opening and closing movements than during the middle portions thereof.
 7. In a valve control assembly of an internal combustion engine having: valve means including a valve reciprocally mounted within the housing of said engine by means of an actuating stem and adapted to open and close intake and exhaust ports communicating with a cylinder of said engine; reciprocating means adapted to engage and move said valve means from a closed to an open position thereof synchronously with the degree of rotation of said engine; a spring means acting against said reciprocating means and adapted to bias said valve in its closed position; the improvement comprising: attenuator means associated with said reciprocating means and adapted to modify the motion of said valve means as actuated by said reciprocating means, said attenuator means comprising a container having a first chamber and a second chamber communicating with said first chamber through an orifice, said first and second chambers being filled with an attenuating liquid, a piston means extending through said orifice and connecting to said reciprocating means to move correspondingly to the movement of said valve means, the relationship of said piston means and said first and chamber being such that the flow resistance offered by said orifice is higher at the termination of the closing movement of said valve means than during the intermediate movement thereof, and a passageway with an associated check valve connecting said first chamber with said second chamber, said check valve being adapted to close said passageway during said closing movement and open the same during the opening movement whereby said attenuator fluid can flow through said passageway, such that the attenuation effected by said attenuator occurs primarily during said closing movement.
 8. The valve control assembly of claim 7 wherein the walls of said piston and/or said second chamber are tapered such that as said piston descends into said second chamber a greater amount of said attenuating fluid must be displaced therefrom for each increment of descent of said piston. 